Percentiles of body mass index in children and adolescents evaluated from different regional German studies

Objectives. Both the Childhood Group of the International Obesity Task Force (IOTF) and the European Childhood Obesity Group (ECOG) recommend to use the body mass index (BMI = weight in kilograms/height in meter(2)) to evaluate overweight and obesity in children and adolescents. Whereas it is customary with adults to use fixed cut off points to define overweight and obesity, in children and adolescents age and sex specific developmental changes in BMI need to be addressed, which are due to physiological alterations of fat mass. Method. Because a national reference population for children and adolescents does not exist in Germany, a BMI reference data set was compiled. Therefore measurements of height and weight from 17 different regional studies including 17147 boys and 17275 girls aged 0 to 18 years were used. Results and conclusions. We recommend the use of the presented percentiles as reference to asses under-and overweight (obesity) in German children and adolescents. In the guidelines of the Arbeitsgruppe Adipositas im Kindes- and Jugendalter(AGA) the 90(th) and 97(th) BMI percentiles as calculated in this reference population are proposed as cut-off points for the definition of overweight and obesity in German children and adolescents.